Noise floor: -78dB acceptable?

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Skyline_UK
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2007/10/06 11:23:29 (permalink)

Noise floor: -78dB acceptable?

When I'm recording an audio track via my Tascam analogue desk I can optimise the various controls to get about -78db flickering on the track in Sonar when nothing else is happening. i.e. that's the background system noise of my desk.

What I do is I arm the track in Sonar (not record) and watch the meter, setting it (right click) at -90db so I can see the lowest part of the noise floor. I manipulate the desk's faders and sends to get the lowest possible figure and that seems the best I can do. It seems ok in terms of the final song, etc. but I just wanted to know if you guys think that's reasonable or crap for a lowest noise floor. [sm=rolleyes.gif]

John

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#1

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    mike_mccue
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    RE: Noise floor: -78dB acceptable? 2007/10/06 12:12:18 (permalink)
    Sure that's fine. That's what drums are for... to mask the noise ;-).

    One thing you didn't fully expplain; Is that just system noise (i.e. no mic plugged in) or is it with a mic set to the correct level for your sound source?

    best regards,
    mike
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    Skyline_UK
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    RE: Noise floor: -78dB acceptable? 2007/10/06 12:24:32 (permalink)
    Thanks Mike. No, no mike plugged in at present. Fantom X6 synth and drum machine plugged in and ready to record from, but I've optimised those for lowest noise by fiddling wth their output levels and their input trims on the desk's channels.

    John

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    #3
    Tonmann
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    RE: Noise floor: -78dB acceptable? 2007/10/06 12:45:50 (permalink)
    Of course, one can't compare it with professional hardware-setups in a studio, but I think it's okay for home recording needs.
    I have a similar noise floor here and it never ment a real problem to me.

    cheers,
    Chris

    ...maybe I never realized the joy till the joy was gone...
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    mike_mccue
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    RE: Noise floor: -78dB acceptable? 2007/10/06 13:02:27 (permalink)
    This also suggests an observation I frequently make while preparing to record... meaning, the subject often times says something empathetic like "are the sound levels ok?" to which I reply "yes, it's good" and then think to myself "you silly well meaning person, you haven't given me anything to adjust the levels too yet." So for much of the work I do I look to the first few seconds of the take to get my levels set, and usually they make a mistake so it all works out.

    The point being, once you start your performance all your pre planning goes out the window. So you can use the work you have just done to learn the general characteristics of how your input chain enhances or aggravates the noise floor and then you can use that knowledge to make judgements on how to react to the actual source material to acchieve good results.

    Does that make sense?

    best regards,
    mike
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    Tonmann
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    RE: Noise floor: -78dB acceptable? 2007/10/06 13:24:03 (permalink)
    What I often hear is the misconception that the noise-floors of all audio-recording simply sum up. So if one has 10 audio-tracks with an almost equal noise-floor of about -78dB, one would end up with a noise-floor up to -28dB (if I calculated correctly).
    This is fortunately nonsense, since it implies that all single tracks are mixed at 0dB, which is hardly ever the case.
    However, even a noise-floor of -78dB can become distrubing if one uses a compressor with lots of gain on that track. In silenced areas of the track the noise will be amplified by the maximum gain of the compressor, resulting in a quite audible noise.
    I'd recommend to use a noise-gate as first FX in that track or a really good FIR-based denoiser plugin.

    @Mike: That's life! One always get the wisdom when it's already done. Same here.

    cheers,
    Chris
    post edited by Tonmann - 2007/10/06 13:33:41

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    altima_boy_2001
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    RE: Noise floor: -78dB acceptable? 2007/10/06 17:20:18 (permalink)
    ORIGINAL: Skyline_UK
    When I'm recording an audio track via my Tascam analogue desk I can optimize the various controls to get about -78db flickering on the track in Sonar when nothing else is happening. i.e. that's the background system noise of my desk.

    If the -78dB reading is from the Sonar meter then that is a peak value. You need to look at RMS when judging noise levels...


    I have an Alesis Multimix 16 FW and with an SM 57 plugged in and mic gain set to a normal, usable level my peak noise is around -80dB and my RMS noise level sits about 10 dB below that. The only time I have a problem with high noise levels is when I'm recording my Marshall combo amp because it's a noisy SOB. The RMS noise floor when it's mic'ed up is around -50 dB on its track so I ended up throwing a noise gate on it a lot.
    #7
    mike_mccue
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    RE: Noise floor: -78dB acceptable? 2007/10/06 17:39:08 (permalink)
    But that's room noise not system noise.

    Some guitar players (like me) think that amp noise is part of the authentic sound.

    best,
    mike
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    bitflipper
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    RE: Noise floor: -78dB acceptable? 2007/10/06 17:52:03 (permalink)
    What I often hear is the misconception that the noise-floors of all audio-recording simply sum up.

    And that isn't true? Or is the misconception not that they aren't additive but that the summing isn't simple? I don't understand how the noise on multiple channels could be anything other than cumulative.


    All else is in doubt, so this is the truth I cling to. 

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    Jim Roseberry
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    RE: Noise floor: -78dB acceptable? 2007/10/06 17:53:23 (permalink)
    Keep in mind you're talking about the peak noise-floor, not the actual average noise floor.
    The average NF will be lower...
    So... it's not as bad as it sounds.

    Best Regards,

    Jim Roseberry
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    #10
    mike_mccue
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    RE: Noise floor: -78dB acceptable? 2007/10/06 17:56:59 (permalink)
    Which, respectfully, is what I said at the onset. Make music not data.

    best,
    mike
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    Tonmann
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    RE: Noise floor: -78dB acceptable? 2007/10/06 18:00:21 (permalink)
    Yes, the misconception is to think it's a "simple" summing like "A + B + C + D", which would only be the case if all tracks are set to 0dB.

    ...maybe I never realized the joy till the joy was gone...
    #12
    Jim Roseberry
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    RE: Noise floor: -78dB acceptable? 2007/10/06 18:00:36 (permalink)
    Or is the misconception not that they aren't additive but that the summing isn't simple? I don't understand how the noise on multiple channels could be anything other than cumulative.


    The noise-floor across tracks is definitely cumulative...
    But his point is that each of those summed tracks is probably attenuated a bit... therefore the cumulative noise-floor isn't directly equal to summing the original (un-attenuated) noise-floor of each track.

    Gates can clean intros/outros... but they won't change the S/N ratio.
    The signal to noise ratio is constant...

    Best Regards,

    Jim Roseberry
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    #13
    Jim Roseberry
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    RE: Noise floor: -78dB acceptable? 2007/10/06 18:01:51 (permalink)
    I agree...

    Best Regards,

    Jim Roseberry
    jim@studiocat.com
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    #14
    Tonmann
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    RE: Noise floor: -78dB acceptable? 2007/10/06 18:04:04 (permalink)

    ORIGINAL: Jim Roseberry

    I agree...

    With yourself?

    ...maybe I never realized the joy till the joy was gone...
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    Jim Roseberry
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    RE: Noise floor: -78dB acceptable? 2007/10/06 18:09:23 (permalink)
    With yourself?


    me, myself, and mike_mccue

    Best Regards,

    Jim Roseberry
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    dreamkeeper
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    RE: Noise floor: -78dB acceptable? 2007/10/06 18:59:31 (permalink)
    So if one has 10 audio-tracks with an almost equal noise-floor of about -78dB, one would end up with a noise-floor up to -28dB (if I calculated correctly).

    Hm, my guess would be -68dB - assuming we're talking about uncorrelated signals here.

    "... must've been another of my dreams ..."
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